While the new E-300 is a higher MP camera, it is still on the consumer level compared to the E-1. Now, I have not yet used the E-300 so it is difficult to give you a truly educated response. However, so many folks think MEGAPIXEL MEGAPIXEL MEGAPIXEL and it's not all about the MEGAPIXEL. You have to consider the chipset size and bit depth when buying digital.
There was a page on (I think) DP Review that showed photographes of all the makes and manufacturers sensor. It blew my mind to see the difference in sensor sizes all the way from point and shoot to DSLR and pro digital camera backs.
You can have two 8 MP cameras and what sets them apart in image quality is the size of those sensors and their bit depth! One thing to keep in mind is that all (thus far) 35mm type DSLR's shoot at 8 bit while compared to a pro digital back shoots at up to 16 bit. Check out DP REVIEW
and have fun doing some research. There's a lot to learn!
All the best,